Sedimentary evidence for recent eutrophication in the northern basin of Lake Taihu,China: human impacts on a large shallow lake     

Wu Jinglu  Huang Chengmin  Zeng Haiao  Gerhard H. Schleser  Rick Battarbee 《Journal of Paleolimnology》2007,38(1):13-23

Environmental change in Lake Taihu and its catchment since the early to middle part of the twentieth century has left a clear geochemical record in the lake sediments. The human activities in the lake and its catchment responsible for the change include agriculture, fishery, urbanisation, sewage and industrial waster disposal. Sediment cores were collected from Meilian Bay of northern Lake Taihu to investigate the record of anthropogenic impacts on the lake’s ecosystem and to assess its natural, pre-eutrophication baseline state. Two marked stratigraphic sediment units were identified on the basis of total phosphorus concentration (TP), pigments, total organic carbon (TOC)/total nitrogen (TN), δ¹³C and δ¹⁵N corresponding to stages in the lake history dominated by phytoplankton, and by aquatic macrophytes. Results show that as TP loading increased from the early 1950s the lake produced sediments with increasing amounts of organic matter derived from phytoplankton. In the early 1950s, the first evidence for eutrophication at the Meilian Bay site is recorded by an increase in C/N values and in sediment accumulation rate, but there is little change in phosphorus concentrations, pigments, δ¹³C and δ¹⁵N at this time. After 1990 a more rapid increase in trophic status took place indicated by increased levels of phosphorus, pigments, δ¹⁵N and by decreased δ¹³C and TOC/TN values in the lake sediments. The first increase in trophic status of the early 1950s results mainly from agricultural development in the catchment. In contrast, the acceleration from ca. 1990 originates from the recent development of fisheries and the urbanisation and industrialisation of the catchment.  相似文献   

Taphonomy and site formation on California's Channel Islands     

Torben C. Rick  Jon M. Erlandson  Ren L. Vellanoweth 《Geoarchaeology》2006,21(6):567-589

Inhabited by humans for over 12,000 calendar years, California's Channel Islands contain thousands of archaeological sites, ranging from dense shell middens and villages to small lithic scatters and camps. Similar to many islands around the world, the Channel Islands have a dearth of burrowing animals and limited historical development leading to generally good preservation of archaeological constituents and relatively high stratigraphic integrity. Despite these favorable preservation conditions, numerous natural and cultural processes have impacted the island's archaeological record. Channel Islands archaeologists, however, have given relatively limited attention to the effects of taphonomic and formation processes. The authors provide an overview of taphonomic and formation processes affecting Channel Islands archaeology, illustrating the importance of regional taphonomic syntheses in the management, preservation, and interpretation of archaeological sites. These data also demonstrate the significance of detailing formation processes in islands and other areas where burrowing rodents and other disturbances are thought to be absent or limited. © 2006 Wiley Periodicals, Inc.  相似文献   

Climate change implications in the northern coastal temperate rainforest of North America     

Colin S. Shanley  Sanjay Pyare  Michael I. Goldstein  Paul B. Alaback  David M. Albert  Colin M. Beier  Todd J. Brinkman  Rick T. Edwards  Eran Hood  Andy MacKinnon  Megan V. McPhee  Trista M. Patterson  Lowell H. Suring  David A. Tallmon  Mark S. Wipfli 《Climatic change》2015,130(2):155-170

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The response of phytoplankton to iron enrichment in Sub-Antarctic HNLCLSi waters: Results from the SAGE experiment     

Jill Peloquin  Julie HallKarl Safi  Walker O. Smith Jr.Simon Wright  Rick van den Enden 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(6):808-823

Areas of high nutrients and low chlorophyll a comprise nearly a third of the world’s oceans, including the equatorial Pacific, the Southern Ocean and the Sub-Arctic Pacific. The SOLAS Sea-Air Gas Exchange (SAGE) experiment was conducted in late summer, 2004, off the east coast of the South Island of New Zealand. The objective was to assess the response of phytoplankton in waters with low iron and silicic acid concentrations to iron enrichment. We monitored the quantum yield of photochemistry (F_v/F_m) with pulse amplitude modulated fluorometry, chlorophyll a, primary productivity, and taxonomic composition. Measurements of F_v/F_m indicated that the phytoplankton within the amended patch were relieved from iron stress (F_v/F_m approached 0.65). Although there was no significant difference between IN and OUT stations at points during the experiment, the eventual enhancement in chlorophyll a and primary productivity was twofold by the end of the 15-day patch occupation. However, no change in particulate carbon or nitrogen pools was detected. Enhancement in primary productivity and chlorophyll a were approximately equal for all phytoplankton size classes, resulting in a stable phytoplankton size distribution. Initial seed stocks of diatoms were extremely low, <1% of the assemblage based on HPLC pigment analysis, and did not respond to iron enrichment. The most dominant groups before and after iron enrichment were type 8 haptophytes and prasinophytes that were associated with ∼75% of chlorophyll a. Twofold enhancement of biomass estimated by flow cytometry was detected only in eukaryotic picoplankton, likely prasinophytes, type 8 haptophytes and/or pelagophytes. These results suggest that factors other than iron, such as silicic acid, light or physical disturbance limited the phytoplankton assemblage during the SAGE experiment. Furthermore, these results suggest that additional iron supply to the Sub-Antarctic under similar seasonal conditions and seed stock will most likely favor phytoplankton <2 ??m. This implies that any iron-mediated gain of fixed carbon will most likely be remineralized in shallow water rather than sink and be sequestered in the deep ocean.  相似文献   

Linking Cree hunters’ and scientific observations of changing inland ice and meteorological conditions in the subarctic eastern James Bay region, Canada     

Marie-Jeanne S. Royer  Thora Martina Herrmann  Oliver Sonnentag  Daniel Fortier  Kenel Delusca  Rick Cuciurean 《Climatic change》2013,119(3-4):719-732

For the Cree First Nation communities of the eastern James Bay region in the Canadian Subarctic, local weather plays a key role in traditional subsistence activities. There is rising concern among the Cree about changes in inland ice conditions as they pose challenges to Cree livelihood, health and culture. Here we contrast Crees’ observations of inland ice conditions and long-term measurements obtained to foster interdisciplinary climate change research between scientists and Cree communities. We compiled qualitative observations of inland ice conditions and compared them with long-term measurements (> 25 years) of air temperature, precipitation and snow depth from three meteorological stations in the Cree territory. Cree hunters observed a weakening of lake ice cover (e.g., change in ice composition and structure, increased rain in winter). Trend analysis of long-term measurements showed a significant increase in mean autumn air temperature as well as in winter and autumn precipitation. By contrasting Cree hunters’ observations with climate data, we identified that an increase in fall and winter precipitation could be causing a weakening of inland ice through a change in its composition (i.e., snow ice instead of congelation ice). We conclude that Cree and scientific knowledge are complementary when investigating and understanding climate change in the Subarctic.  相似文献   

Smithsonian institution’s global volcanism network     

Rick Wunderman 《Bulletin of Volcanology》2001,63(2-3):221-222

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North American Earth Science Megaproject Continuum, Part 3: New Canadian EON-ROSE Program     

Katherine Boggs  David Eaton  Thomas James  Roy Hyndman  Malaika Ulmi  Pascal Audet  Ed Johnston  Michael Sideris  Ron Clowes  Julie Elliott  Jeff Freymueller  Paul Kushner  Kristin Morell  Derek Schutt  Rick Aster  Frank Vernon  Michael Hedlin  Catherine de Groot-Hedlin  Eric Donovan  Roland Stull 《《地质学报》英文版》2018,92(Z1):12-13

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Observations and Impacts from the 2010 Chilean and 2011 Japanese Tsunamis in California (USA)   总被引：3，自引：0，他引：3  

Rick I. Wilson  Amanda R. Admire  Jose C. Borrero  Lori A. Dengler  Mark R. Legg  Patrick Lynett  Timothy P. McCrink  Kevin M. Miller  Andy Ritchie  Kara Sterling  Paul M. Whitmore 《Pure and Applied Geophysics》2013,170(6-8):1127-1147

The coast of California was significantly impacted by two recent teletsunami events, one originating off the coast of Chile on February 27, 2010 and the other off Japan on March 11, 2011. These tsunamis caused extensive inundation and damage along the coast of their respective source regions. For the 2010 tsunami, the NOAA West Coast/Alaska Tsunami Warning Center issued a state-wide Tsunami Advisory based on forecasted tsunami amplitudes ranging from 0.18 to 1.43 m with the highest amplitudes predicted for central and southern California. For the 2011 tsunami, a Tsunami Warning was issued north of Point Conception and a Tsunami Advisory south of that location, with forecasted amplitudes ranging from 0.3 to 2.5 m, the highest expected for Crescent City. Because both teletsunamis arrived during low tide, the potential for significant inundation of dry land was greatly reduced during both events. However, both events created rapid water-level fluctuations and strong currents within harbors and along beaches, causing extensive damage in a number of harbors and challenging emergency managers in coastal jurisdictions. Field personnel were deployed prior to each tsunami to observe and measure physical effects at the coast. Post-event survey teams and questionnaires were used to gather information from both a physical effects and emergency response perspective. During the 2010 tsunami, a maximum tsunami amplitude of 1.2 m was observed at Pismo Beach, and over $3-million worth of damage to boats and docks occurred in nearly a dozen harbors, most significantly in Santa Cruz, Ventura, Mission Bay, and northern Shelter Island in San Diego Bay. During the 2011 tsunami, the maximum amplitude was measured at 2.47 m in Crescent City Harbor with over $50-million in damage to two dozen harbors. Those most significantly affected were Crescent City, Noyo River, Santa Cruz, Moss Landing, and southern Shelter Island. During both events, people on docks and near the ocean became at risk to injury with one fatality occurring during the 2011 tsunami at the mouth of the Klamath River. Evaluations of maximum forecasted tsunami amplitudes indicate that the average percent error was 38 and 28 % for the 2010 and 2011 events, respectively. Due to these recent events, the California tsunami program is developing products that will help: (1) the maritime community better understand tsunami hazards within their harbors, as well as if and where boats should go offshore to be safe, and (2) emergency managers develop evacuation plans for relatively small “Warning” level events where extensive evacuation is not required. Because tsunami-induced currents were responsible for most of the damage in these two events, modeled current velocity estimates should be incorporated into future forecast products from the warning centers.  相似文献   

Book review: Groundwater around the World: A Geographic Synopsis,by Jean Margat and Jac van der Gun (CRC Press, 2013)     

Rick Brassington 《Hydrogeology Journal》2014,22(3):743-744

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Shell Middens,Cultural Chronologies,and Coastal Settlement on the Rhode River Sub‐Estuary of Chesapeake Bay,Maryland, USA     

Torben C. Rick  Leslie A. Reeder‐Myers  C. Jane Cox  Stephanie T. Sperling  Alex Jansen  Anson H. Hines 《Geoarchaeology》2014,29(5):371-388

North America's Atlantic Coast has been a focus of human settlement and subsistence for millennia, but sea‐level rise, sedimentation, and other processes pose significant challenges for archaeological research. Radiocarbon dating of 31 shell middens near the Rhode River Estuary, Maryland provides an opportunity to evaluate human land use, settlement, and cultural chronologies on the Chesapeake Bay. Sixty calibrated radiocarbon dates on eastern oyster (Crassostrea virginica) shell and charcoal demonstrate that Native Americans, colonial, and historic peoples harvested oysters and other shellfish from at least 3200 years ago through the 19th century. The number of dated sites increases during the Late Woodland period after about 1000 cal yr B.P., a factor probably related to greater site visibility and preservation, as well as increased human exploitation of the watershed. Accumulation rates for five of the shell middens provide preliminary indications that some of the sites accumulated rapidly suggesting, along with other evidence, that many of the region's shell middens were logistical or perhaps seasonal camps. Our study demonstrates the importance of regional watershed surveys and radiocarbon dating programs to help build and refine cultural chronologies in coastal regions threatened by sea‐level rise and other processes.  相似文献